The smoking taste of tobacco stems

ABSTRACT

The smoking taste of tobacco stems is improved by a treating cycle wherein a vacuum is first drawn on the product and then the vacuum is broken by the introduction of superheated steam until air pressure of the atmosphere in the stems has returned substantially to ambient atmospheric pressure. The steam treated stems are maintained in this condition for a period of at least 24 hours.

United States Patent Inventors John T. Ashworth;

Leonard V. Kielpinski, Richmond, Va. 71 1.234

Mar. 7, 1968 Jan. 26, 1971 The American Tobacco Company New York, N.Y.

a corporation of New Jersey Appl. No. Filed Patented Assignee THE SMOKING TASTE OF TOBACCO STEMS 5 Claims, No Drawings US. Cl 131/140, 131/133 Int. Cl A24b 03/18, A24b 03/12 Field of Search 131/140,

140A, 133A;131/140P,133, 140

References Cited UNITED STATES PATENTS 11/1968 de la Burde i. 7/1940 Palmer 10/1940 Smith et a1... 4/1947 Berger et a1. 7/1966 Lindstrom FOREIGN PATENTS 4/1949 Great Britain Primary Examiner-Melvin D. Rein Attorney-Pennie, Edmonds, Morton, Taylor and Adams PATENTEU mass m 3 557' 798 SHEU 2 [IF 3 PATENTED JAN26 19m sum 3 or 3 Twew/ u 4 .r

lmvS ll 00 H THE SMOKING TASTE OF TOBACCO STEMS This invention relates to improvement of the quality of tobacco and, more particularly, to improvement of the smoking taste of tobacco stems.

It has been known for over a century (US. Pat. No. 22,668) that the color of tobacco stems could be darkened by steaming them for a period of about 40 hours, and the same type of treatment has been used to darken cigar leaf (US. Pat. No. 152,024). Shorter periods of time for darkening tobacco have been achieved by using superheated or high pressure steam (US. Pat. No. 2,419,109), and ordering of tobacco has also been carried out by the alternate use of a vacuum and steam (US. Pat. No. 123,011). These treatments, and many other variations thereof, have been used on a variety of tobacco products, but although they have improved the color of the tobacco it is still an accepted fact that the characteristically harsh smoking taste of the stem constituent of the tobacco has not been significantly altered.

We have now discovered, however, that a specific steam treatment of tobacco stems, carried out prior to their conventional processing for production of smoking products, appears to alter some component or components of the stems to the extent that subsequent conventional processing of the stems results in a smoking product greatly reduced in the off or harsh taste formerly attributable to its stem content. This specific steam treatment consists essentially of subjecting a body of the raw tobacco stems, prior to all other extraction and chemical processing treatments, to the action of a vacuum and then breaking the vacuum by the admission of superheated steam to the body of stems.

The reason for the improved results obtained by the practice of the invention is not fully understood. However, it appears likely that some component of the stems is chemically altered because the improvement resulting from the aforementioned vacuum-steam cycle is not achieved when the stems have been subjected to some prior extraction or heating step, or both. For example, when the stems are waterextracted and the separated fibrous and aqueous phases are heated and are then recombined to form reconstituted tobacco, there is no significant improvement in the harsh smoking taste attributable to the stem constituent. Moreover, when the stems are water-extracted and the separated fibrous and aqueous phases are recombined pursuant to the conventional practice of forming reconstituted tobacco, and the resulting reconstituted tobacco is given the vacuum-steam treatment used in practicing the present invention, there is again little change inv the harsh taste of the smoke caused by the presence of the stem components. For the vacuum-steam treatment of this invention to ,make a significant improvement in the smoking taste of the stems, they must be subjected to the specified treatment prior to any other changes being made in the stem constituents by prior extraction or chemical processing treatment.

In treating any tobacco stern constituent pursuant to this invention, the stem material is charged to a vessel capable of being evacuated. A vacuum is then drawn on the vessel to a pressure below about 1 inch of mercury absolute and advantageously to about 0.2 inch or less. After the desired vacuum has been established, it is broken by admitting superheated steam. The extent of superheating is determined by practical considerations, such as the availability of the superheated steam and time requirements. The effectiveness of the steam treatment in improving the smoking taste of the stems increases with increasing steam temperature and with increasing temperature within the stern mass of the end of the steam treatment'Superheated steam under 5 pounds pressure appears to be wholly satisfactory in practicing the invention but higher pressure steam, such as -20 p.s.i. steam, can be used with advantage. Although the incoming steam is cooled as it enters the evacuated tobacco mass, the use of superheated steam assures an effectively high final temperature in the mass of stems, a final temperature within the range of about 200220 F. generally being consonant with markedly improved smoking taste of the stems.

The superheated steam is let into the evacuated mass of tobacco stems sufficicntly slowly to promote whatever chemical action takes place to produce the taste improvement characteristic of the practice of the invention. In general, a steam introduction period of at least about 5 minutes appears to provide adequate time for effective darkening of the fibers, although we presently prefer to break the vacuum with the superheated steam over a period of 15 to 30 minutes. After the pressure in the treating vessel has returned substantially to that of the ambient atmosphere, the steam introduction is terminated. A curing period of at least 24 hours is advantageous following the treatment. Although a single cycle of this vacuum steam treatment is effective in improving the smoking taste of the stems, two or more cycles appear to progressively promote the desired improvement, and in general we presently prefer to subject the stem material to four or more substantially identical cycles to complete the treatment.

The following specific example is illustrative of the practice of the invention. For the purpose of this example, a number of tests were run to compare the results of the practice of the invention with treatments outside the scope of the invention:

1. ln the first test, tobacco stems in a tobacco mass were subjected to conventional water extraction with grinding and beating to form an aqueous phase and a fibrous phase. The two phases were separated, the aqueous phase was concentrated, the fibrous phase was converted into sheet form and then the aqueous phase was returned as an impregnant for the sheetlike fibrous phase. The resulting reconstituted tobacco sheet was subjected to evacuation to at least 0.5 inch of mercury absolute and the vacuum was then broken by admitting superheated steam at 5 p.s.i. into the tobacco mass over a period of about 20 minutes with a resulting final tobacco temperature of about 200 F. When smoked, the resulting tobacco product had the unacceptable harsh taste characteristic of the starting stem material.

2. 1n the second test, a separated fibrous phase obtained from a mass of stems as described in Test 1 was given the same vacuum-steam treatment described in that test but prior to recombining of the thustreated fibrous phase and the concentrated aqueous phase. The resulting reconstituted tobacco product had the characteristic harsh smoking taste of the untreated stem content.

3. in the third test, a mass of the same raw stems was given the vacuum treatment described in Test 1 but the vacuum was broken by admitting the ambient atmosphere rather than with superheated steam. The thus-treated stem material was then worked up into reconstituted sheet as described in Test 1, and when this sheet was smoked it had the characteristic harsh taste attributable to the initial stem content.

4. In the fourth test, a mass of the same raw stems was not evacuated but was given the steam treatment described in Test 1. The thus-treated stem material was then worked up into reconstituted sheet as described in Test 1, and when this sheet was smoked it had the same harsh taste as in each of the preceding tests.

5. in the fifth test, a massof the same raw stern material was given the treatment of the present invention by evacuating a mass of the raw stems to at least 0.5 inch of mercury absolute and the vacuum was then broken by admitting superheated steam at 5 psi. into the stem mass over a period of about 20 minutes with a resulting final tobacco temperature of about 200 F. When the thus-treated stem material was worked up into reconstituted sheet as described in Test 1, and was then smoked, the harsh taste attributable to the initial stem content was significantly alleviated and the product had an acceptable smoking taste.

6. in the sixth test, a mass of the same raw stem material was given the vacuum-steam treatment described in Test 5. This same vacuum-steam treating cycle was repeated until a total of four cycles had been performed. When the thus-treated stem material was worked up into reconstituted sheet as described in Test l and was then smoked, its smoke was substantially free of the harsh taste characteristic of the raw stem material.

lclaim:

l. The method of improving the smoking taste of tobacco stems which consist essentially of subjecting a body of raw tobacco stems, prior to all other extraction and chemical processing treatments, to the action of a vacuum and then breaking the vacuum by the admission of superheated steam to the body of stems until the pressure of the resulting atmosphere in the stems has returned substantially to that of ambient atmospheric pressure, and continuing to hold the steamtreated stems in the latter condition for a period of at least about 24 hours.

2. The method according to claim 1 in which the vacuum is below 1 inch of mercury absolute and the superhcatedsteam is under superatmospheric' pressure up to 15 pounds per square inch.

3. The methodaccording to'claim 1' inwhich the steam is admitted for a period of time sufficientto raise the temperature of the body of stems to a value within the range of about 200 0 220F.

4. The method according to claim l in which the vacuum is broken by admission of the steam over a period of at least about 5 minutes.

5. The method according to claim l in which the vacuumsteam treatment is repeated for a total of at least 2 cycles Patent $10. 3, 57, 793 Dntud January 26, 1971 JOHN TtASHWORTH et a1 Inventorfiz) It is cartificd Lhnt: (error appears: in thc above-identified mu-1:

and LhnL said Lt-Ltcrs Patent: arc hereby corrected as shown below:

The TITLE should read Ii-IPROVING THE SMOKING TASTE OF TOBACCO STEMS Signed and sealed this 29th day of June 1971 (SEAL) Attest:

M.FLETCHER JR. WILLIAM E SCHUYLEH, JR. fi t t ing Officer Commissioner of Patents 

2. The method according to claim 1 in which the vacuum is below 1 inch of mercury absolute and the superheated steam is under superatmospheric pressure up to 15 pounds per square inch.
 3. The method according to claim 1 in which the steam is admitted for a period of time sufficient to raise the temperature of the body of stems to a value within the range of about 200* to 220*F.
 4. The method according to claim 1 in which the vacuum is broken by admission of the steam over a period of at least about 5 minutes.
 5. The method according to claim 1 in which the vacuum-steam treatment is repeated for a total of at least 2 cycles. 